Henry had a full life, travelling the world, fighting in the war, and eventually starting his own business and making a fortune.

After his wife died, he stopped leaving his home. As a result, no one had seen him since 1986. He continued to collect artefacts though, and hired security personal to make his house well-guarded.

By 2008, he was dying from a failing heart. He had had three heart attacks and a failed bypass. By this time, he was eighty-odd years old. Terrified to die, he activated the Pulse, an artefact, taking it into his bed believing it to be a healing device. The pulse started to leak dangerous radiation, and Torchwood stepped in, infiltrating his house and neutralising the device.

DrOwen Harper, technically dead but reanimated, was assigned to enter Parker's home as his undead state allowed him to get past heat sensors and other security devices. During an ensuing discussion with Harper, Parker revealed intimate, and unexplained, knowledge of the Torchwood 3 team, suggesting some level of recent surveillance. Soon after Harper deactivated the pulse, Parker died of natural causes; Harper attempted artificial respiration to keep the man alive, but was unable to produce breath to do so. (TV: A Day in the Death)

Henry Parker shared some similarities with another wealthy collector of alien artefacts, Henry van Statten. (TV: Dalek) Both kept their collections hidden behind massive security, both attempted to use alien tech for their own ends, both included living creatures among their collections, and both collections included pieces of Cybermen.